This invention relates to mechanism for locking a linearly movable rod in selected positions of adjustment. The rod may be an inflexible rigid member, such as a piston rod, control rod, shaft, strut or leg structure. Alternatively, the rod can be a flexible member such as a cable, rope, hose, or wire.
Usually the rod will have a circular cross section, although other cross sections are possible, such as square, rectangular triangular, or hexagonal. The term "movable rod" will be used herein to include a flexible or inflexible elongated member movable in the direction of its axis.
In one embodiment of the invention the movable rod extends through a housing that has two annular elastomeric members encircling the rod outer surface. The annular elastomeric members are initially formed with internal drameters less than the outer diameter of the rod. In their normal relaxed states the elastomeric members frictionally grip the outer surface of the rod to prevent rod movement. The support housing communicates with a compressed air source so that when a control valve is opened to admit compressed air into the housing the increased pressure within the housing acts against the elastomeric members to expand the members away from the rod surface, thereby enabling the rod to be moved relative to the housing. In an absolute sense the housing may be stationary and the rod movable, or the housing may be movable and the rod stationary. In either case the rod has movement relative to the housing.
A general object of the invention is to provide a rod locking mechanism that can be remotely actuated. Another object is to provide a rod locking mechanism that can be manufactured at relatively low cost.